Virtual prototyping of a car turn-signal switch using haptic feedback

The present work describes the virtual prototyping procedure of car turn-signal switches using a dedicated haptic feedback system. Although turn-signal switches have mechanisms with simple geometry, simulating the “feeling” during its operation is still a challenge. In order to allow ergonomics designers to directly assess the comfort of operation, a dedicated haptic system was developed for reproducing the force feedback that would characterize a real turn-signal switch. For the accurate haptic feedback generation and rendering purpose, a detailed computer-aided design model of the switch was developed together with a multibody simulation. For the design purpose a novel method for the synthesis of the cam mechanism was also developed, starting from an imposed force profile that was previously validated on the haptic device, for which the cam geometry is determined. Thus, the proposed approach enables the designer to also design the “feel” of the switch, and directly manufacture a good model, simplifying the usual iterative process necessary to implement the desired force profile. Finally, an example of virtual prototyping of a turn-signal switch is presented demonstrating the usability of the proposed method and the haptic system.     

Haptic interaction and volume modeling techniques for realistic dental simulation

We present haptic simulation and volume modeling techniques for a virtual dental training system. The system allows dental students to learn dental procedures and master their skills with realistic tactual feelings. It supports various dental procedures, such as dental probing, to diagnose carious lesions, drilling operation for cavity preparation, and filling the prepared cavities with amalgam. The system requires fast and stable haptic rendering and volume modeling techniques working on the virtual tooth. Collision detection and force computation are implemented on an offset surface in volumetric representation to simulate reasonable physical interactions between dental tools with a certain volume and the teeth model. To avoid discrete haptic feeling due to the gap between the fast haptic process (1 KHz) and much slower visual update frequency (30 Hz) during drilling and filling the cavities, we employed an intermediate implicit surface to be animated between the original and target surfaces. The volumetric teeth model is converted into a geometric model by an adaptive polygonization method to maintain sharp features in every visual frame. Volumetric material properties are represented by stiffness and color values to simulate the resistance and texture information depending on anatomical tissues. Finally, we made a dental workbench to register sensory modalities like visual, auditory and haptic sensation.     

Haptic rendering for dental training system

Immersion and interaction are two key features of virtual reality systems, which are especially important for medical applications. Based on the requirement of motor skill training in dental surgery, haptic rendering method based on triangle model is investigated in this paper. Multi-rate haptic rendering architecture is proposed to solve the contradiction between fidelity and efficiency requirements. Realtime collision detection algorithm based on spatial partition and time coherence is utilized to enable fast contact determination. Proxy-based collision response algorithm is proposed to compute surface contact point. Cutting force model based on piecewise contact transition model is proposed for dental drilling simulation during tooth preparation. Velocity-driven levels of detail haptic rendering algorithm is proposed to maintain high update rate for complex scenes with a large number of triangles. Hapticvisual collocated dental training prototype is established using half-mirror solution. Typical dental operations have been realized including dental caries exploration, detection of boundary within dental cross-section plane, and dental drilling during tooth preparation. The haptic rendering method is a fundamental technology to improve immersion and interaction of virtual reality training systems, which is useful not only in dental training, but also in other surgical training systems. Supported by National Natural Science Foundation of China (Grant Nos. 60605027, 50575011), National High-Tech Research & Development Program of China (Grant No. 2007AA01Z310)     

Simultaneous remote haptic collaboration for assembling tasks

Stand-alone virtual environments (VEs) using haptic devices have proved useful for assembly/disassembly simulation of mechanical components. Nowadays, collaborative haptic virtual environments (CHVEs) are also emerging. A new peer-to-peer collaborative haptic assembly simulator (CHAS) has been developed whereby two users can simultaneously carry out assembly tasks using haptic devices. Two major challenges have been addressed: virtual scene synchronization (consistency) and the provision of a reliable and effective haptic feedback. A consistency-maintenance scheme has been designed to solve the challenge of achieving consistency. Results show that consistency is guaranteed. Furthermore, a force-smoothing algorithm has been developed which is shown to improve the quality of force feedback under adverse network conditions. A range of laboratory experiments and several real trials between Labein (Spain) and Queen’s University Belfast (Northern Ireland) have verified that CHAS can provide an adequate haptic interaction when both users perform remote assemblies (assembly of one user’s object with an object grasped by the other user). Moreover, when collisions between grasped objects occur (dependent collisions), the haptic feedback usually provides satisfactory haptic perception. Based on a qualitative study, it is shown that the haptic feedback obtained during remote assemblies with dependent collisions can continue to improve the sense of co-presence between users with regard to only visual feedback.     

Experiments in haptic-based authentication of humans

With the rapid advancement of the technological revolution, computer technology such as faster processors, advanced graphic cards, and multi-media systems are becoming more affordable. Haptics technology is a force/tactile feedback technology growing in disciplines linked to human–computer interaction. Similar to the increasing complexity of silicon-based components, haptics technology is becoming more advanced. On the other hand, currently available commercial haptics interfaces are expensive, and their application is mostly dedicated to enormous research projects or systems. However, the trend of the market is forcing haptic developers to release products for use in conjunction with current keyboards and mice technologies. Haptics allows a user to touch, fell, manipulate, create, and/or alter simulated three-dimensional objects in a virtual environment. Most of the existing applications of haptics are dedicated to hone human physical skills such as sensitive hardware repair, medical procedures, handling hazardous substances, etc. These skills can be trained in a realistic virtual world, and describe human behavioural patterns in human–computer interaction environments. The measurement of such psychomotor patterns can be used to verify a person’s identity by assessing unique-to-the-individual behavioural attributes. This paper explores the unique behaviour exhibited by different users interacting with haptic systems. Through several haptic-based applications, users’ physical attributes output data from the haptic interface for use in the construction of a biometric system.

Influences of haptic communication on a shared manual task

With the advent of new haptic feedback devices, researchers are giving serious consideration to the incorporation of haptic communication in collaborative virtual environments. For instance, haptic interactions based tools can be used for medical and related education whereby students can train in minimal invasive surgery using virtual reality before approaching human subjects. To design virtual environments that support haptic communication, a deeper understanding of humans′ haptic interactions is required. In this paper, human′s haptic collaboration is investigated. A collaborative virtual environment was designed to support performing a shared manual task. To evaluate this system, 60 medical students participated to an experimental study. Participants were asked to perform in dyads a needle insertion task after a training period. Results show that compared to conventional training methods, a visual-haptic training improves user′s collaborative performance. In addition, we found that haptic interaction influences the partners′ verbal communication when sharing haptic information. This indicates that the haptic communication training changes the nature of the users′ mental representations. Finally, we found that haptic interactions increased the sense of copresence in the virtual environment: haptic communication facilitates users′ collaboration in a shared manual task within a shared virtual environment. Design implications for including haptic communication in virtual environments are outlined.     

Haptic force control based on impedance/admittance control aided by visual feedback

This paper demonstrates a haptic device for interaction with a virtual environment. The force control is added by visual feedback that makes the system more responsive and accurate. There are two popular control methods widely used in haptic controller design. First, is impedance control when user motion input is measured, and then, the reaction force is fed back to the operator. The alternative method is admittance control, when forces exerted by user are measured and motion is fed back to the user. Both, impedance and admittance control are also basic ways for interacting with a virtual environment. In this paper, several experiments were performed to evaluate the suitability of force-impedance control for haptic interface development. The difference between conventional application of impedance control in robot motion control and its application in haptic interface development is investigated. Open loop impedance control methodology is implemented for static case and a general-purpose robot under open loop impedance control was developed as a haptic device, while a closed loop model based impedance control was used for haptic controller design in both static and dynamic case. The factors that could affect to the performance of a haptic interface are also investigated experimentally using parametric studies. Experimental results for 1 DOF rotational motion and 2 DOF planar translational motion systems are presented. The results show that the impedance control aided by visual feedback broaden the applicability of the haptic device and makes the system more responsive and accurate.

A Survey of Haptic Rendering Techniques

Computer Graphics technologies have developed considerably over the past decades. Realistic virtual environments can be produced incorporating complex geometry for graphical objects and utilising hardware acceleration for per pixel effects. To enhance these environments, in terms of the immersive experience perceived by users, the human's sense of touch, or haptic system, can be exploited. To this end haptic feedback devices capable of exerting forces on the user are incorporated. The process of determining a reaction force for a given position of the haptic device is known as haptic rendering. For over a decade users have been able to interact with a virtual environment with a haptic device. This paper focuses on the haptic rendering algorithms which have been developed to compute forces as users manipulate the haptic device in the virtual environment.     

Perception-based lossy haptic compression considerations for velocity-based interactions

The ability of technology to transmit multi-media is very dependent on compression techniques. In particular lossy compression has been used in image compression (jpeg) audio compression (mp3) and video compression (mpg) to allow the transmission of audio and video over broadband network connections. Recently the sense of touch or haptics is becoming more important with its addition in computer games or in cruder applications such as vibrations in a cell phone. As haptic technology improves the ability to transmit compressed force sensations becomes more critical. Most lossy audio and visual compression techniques rely on the lack of sensitivity in humans to pick up detailed information in certain scenarios. Similarly limitations in the sensitivity of human touch could be exploited to create haptic models with much less detail and thus requiring smaller bandwidth. The focus of this paper is on the force thresholds of the human haptic system that can be used in a psychophysically motivated lossy haptic (force) compression technique. Most of the research in this field has measured the just noticeable difference (JND) of the human haptic system with a human user in static interaction with a stationary rigid object. In this paper our focus involves cases where the human user or the object are in relative motion. An example of such an application would be the haptic rendering of the user’s hand in contact with of a high-viscous material or interacting with a highly deformable object. Thus an approach is presented to measure the force threshold based on the velocity of the user’s hand motion. Two experiments are conducted to detect the absolute force threshold (AFT) of the human haptic system using methodologies from the field of psychophysics. The AFTs are detected for three different ranges of velocity of the user’s hand motion. This study implies that when a user’s hand is in motion fewer haptic details are required to be stored calculated or transmitted. Finally the implications of this study on a more complete future study will be discussed.

Collaborative virtual sculpting with haptic feedback

This paper introduces a haptic virtual environment in which two users can collaboratively sculpt a virtual clay model, working from different physical locations connected by the internet. They view their virtual sculpting tools and the clay model in 3D, feel the tool’s pressure on the clay as they work, and have their hands co-located with the view of the tool and model. Since the sculptors have independent views of the same logical environment, they can work at different zoom levels, and be in different coordinate systems, even spinning ones, at the same time. This provides them with the capability to explore new styles of collaborative creativity, working off each other’s initiative where appropriate. The system was designed to allow unrestrained, asynchronous behaviour by the collaborating sculptors. The paper describes the hardware as well as the algorithms behind the deformability of the clay surface and the communications model enabling the distance collaboration. It gives an explanation of the simple conflict resolution mechanism that haptic feedback facilitates and also reports on the results of a qualitative study into the creativity benefits of such a collaborative system.     

用于实时柔性触觉再现的平行菱形链连接模型

精度高且实时性好的柔性触觉变形模型是实现触觉再现系统的关键。提出了一种新的基于物理意义的平行菱形链连接触觉变形模型,系统中各个链结构单元相对位移的叠加对外等效为物体表面的变形,与之相连的弹簧弹性力的合力等效为物体表面的接触力。使用Delta 6-DOF手控器,建立了触觉再现实验系统,对柔性体的接触变形和实时虚拟触觉反馈进行仿真, 实验结果表明所提出的模型不仅计算简单,而且能够保证触觉接触力和形变计算具有较高精度,满足虚拟现实系统对精细作业和实时性的要求。     

Desktop haptic virtual assembly using physically based modelling

This research investigates the feasibility of using a desktop haptic virtual environment as a design tool for evaluating assembly operations. Bringing virtual reality characteristics to the desktop, such as stereo vision, further promotes the use of this technology into the every day engineering design process. In creating such a system, the affordability and availability of hardware/software tools is taken into consideration. The resulting application combines several software packages including VR Juggler, open dynamics engine (ODE)/open physics abstraction layer (OPAL), OpenHaptics, and OpenGL/GLM/GLUT libraries to explore the benefits and limitations of combining haptics with physically based modelling. The equipment used to display stereo graphics includes a Stereographics emitter, Crystal Eyes shutter glasses, and a high refresh rate CRT Monitor. One or two-handed force feedback is obtained from various PHANTOM haptic devices from SensAble Technologies Inc. The application’s ability to handle complex part interactions is tested using two different computer systems, which approximate the higher and lower end of a typical engineer’s workstation. Different test scenarios are analyzed and results presented.     

实时多组织虚拟手术的反馈力模拟

为了在虚拟下颌整形手术系统中提供实时和真实的触觉交互,分别构建了基于虚拟中介平面的推操作触觉模型、基于粘附力的拉操作触觉模型和基于非线性粘弹性的针刺触觉模型,以模拟皮肤拉钩、整形镊和针的典型手术操作;同时通过相邻组织间的动态触觉约束建立了多组织联合形变模型,以避免表面弹簧-质点模型形变过程中可能出现的表面间相互穿透的异常现象;并进一步将触觉交互模型和多组织形变模型集成于虚拟下颌手术系统,从而为医生提供一个手术训练的虚拟平台.触觉感知和交互效率的实验结果表明,通过触觉交互识别皮肤、肌肉和骨骼能够获得较高的识别正确率,并能提供实时的触觉和视觉交互体验.     

Modeling and deforming a virtual dense elastic object with the haptic device PHANToM

In recent years, there have been various problems in medical treatments, of which human error by the surgeon in an operation is one of the most serious. In order to minimize human error in an operation, we need a medical training system by which inexperienced surgeons can try operating again and again to improve their skill. In this research, we construct a system of modeling a virtual dense elastic object, and deforming that object using a haptic device called PHANToM. In the system which we construct, we use two PCs to distribute the process of calculation, and SCRAMNet+ is used to connect each PC. PHANToM is used to operate on the object and to express the force which is generated from the deformation of the object. We represent the dense object by using voxels and tetrahedrons, and the elastic object by using a spring-mass model. A virtual dense elastic object is obtained by computed tomography (CT) or magnetic resonance imaging (MRI) to express the patient’s organs.     

带有力感觉的显微外科手术血管的仿真研究

随着虚拟现实技术的进步,带有力感觉的仿真研究迅速发展,特别是在医学上得到了广泛应用。利用虚拟现实技术取代效率低下的常规培训,可以大大减少所需的培训时间和昂贵的动物实验费用。针对复杂的显微外科手术的血管缝合,作者建立了可用于大夫培训、手术规划的虚拟现实系统。其中的交互设备采用了具有力反馈功能的PHANTOM—Desktop,使用与之配套的GHOSTSDK软件开发包,建立虚拟环境。考虑到柔性体仿真的实时性和真实性要求,采用了质量一弹簧模型的建模方法。在完成了对虚拟环境中柔性平面仿真的基础上,成功实现了带有力感觉的显微外科血管穿刺的虚拟仿真。     

Networked multiplayer cooperative interaction using decoupled motion control method in a shared virtual environment with haptic,visual and movement feedback

This paper focuses on multiplayer cooperative interaction in a shared haptic environment based on a local area network. Decoupled motion control, which allows one user to manipulate a haptic interface to control only one‐dimensional movement of an avatar, is presented as a new type haptic‐based cooperation among multiple users. Users respectively move an avatar along one coordinate axis so that the motion of the avatar is the synthesis of movements along all axes. It is different from previous haptic cooperation where all users can apply forces on an avatar along any direction to move it, the motion of which completely depends on the resultant force. A novel concept of movement feedback is put forward where one user can sense other users’ hand motions through his or her own haptic interface. The concept can also be explained wherein one person who is required to move a virtual object along only one axis can also feel the motions of the virtual object along other axes. Movement feedback, which is a feeling of motion, differs from force feedback, such as gravity, collision force and resistance. A spring‐damper force model is proposed for the computation of motion feedback to implement movement transmission among users through haptic devices. Experimental results validate that movement feedback is beneficial for performance enhancement of such kind of haptic‐based cooperation, and the effect of movement feedback in performance improvement is also evaluated by all subjects.Copyright © 2012 John Wiley & Sons, Ltd.     

Incorporating Tactile Cues into Human‐Centered Virtual Product Design

This study introduces a high‐fidelity tactile feedback mechanism to capture ergonomics attributes of users inside virtual product development cycle. The research question posed regards whether the tactile feedback mechanism in virtual experiment proposes high fidelity of ergonomics results when compared to physical experiment outcomes. This question was evaluated through an objective and a subjective study. Objective study was composed of an ergonomics product assessment experiment, where two different cart designs (a commercial cart and a prototype model) were evaluated for ergonomic adequacy (L4/L5 compression forces). Subjective evaluation was consisted of a questionnaire to assess subjects' preferences regarding which cart model they preferred in three different design categories; maneuverability, accessibility, and ergonomics. Results showed that tactile feedback mechanism was able to replicate the physical test conditions in virtual environment with high fidelity, and prototype cart model received higher mean ratings when compared to commercial cart model in each design category.     

Virtual prototyping of mechanical systems with tool mediated haptic feedback

Haptic feedback usually involves two types of stimulation forces: forces that address the touch sense and forces that address the kinesthetic perception. Touch forces have a low intensity and a complex structure since they reflect contact phenomena where friction plays an important role. Therefore, they are quite difficult to simulate. Virtual prototyping with haptic feedback should ideally involve both types of forces, but the integration of the touch feeling makes the simulator very complex. In this paper, we present a novel concept for virtual prototyping in which the touch interaction is separated from the kinesthetic force feedback. This is possible using a prototype that has a real part undertaking the touch interaction and a virtual part that simulate feedback for the kinesthetic forces. In this way, a full haptic interaction with the virtual prototype is established by means of a device that provides a realistic simulation of the product. In order to illustrate the concept, several experiments have been carried out for the case of specific subsystems of a car, which are particularly involved in the driver–car interaction: steering system, clutch pedal and the gearshift. A user test is described in the last part as well as the conclusions of the research.     

Passive internet-based crane teleoperation with haptic aids

Crane operation is a challenging task, due to the combined problem of obstacle avoidance and load swing suppression in underactuated conditions. This paper presents a human-machine interface that increases the operator’s perception of a gantry crane’s workspace. With this aim, a virtual environment resembling the workspace is connected with a haptic device. This allows the user to receive not only visual but also tactile feedback, thus increasing maneuvering safety. Additionally, this capability is integrated in a teleoperation setup, adopting a passivity-based control approach that guarantees overall stability. This includes also the design of controllers by means of the IDA-PBC method. Experimental results carried out with a laboratory crane show its feasibility for internet-based teleoperation and demonstrate the improvements on the system performance.